Wide field

Choosing a Star Tracker

When it comes to astrophotography, a star tracker allows you to take better images. Your exposure lengths are no longer limited to 30-seconds or less due to a moving sky, and you can dial back camera settings like ISO and F-stop.

Equatorial camera mounts are designed to align with the polar axis of the night sky so you can take long-exposure images that are free of star trailing. Astrophotography demands long-exposure tracked images to collect as much signal (light) as possible, and that is exactly what a star tracker allows you to do.

This summer, I had the opportunity to review a new star tracker for astrophotography, the Fornax Mounts LighTrack II. From the mechanical design to the polar alignment procedure, this portable tracking camera mount is very different from any astrophotography mount I have ever used before.

It created the perfect opportunity to compare this camera tracker against some of the competing models in this category, in terms of overall user experience and performance. In this post, I’ll discuss the topic of using a star tracker for astrophotography, and which one I like using most.

The star trackers shown above are capable of accurately tracking the night sky for long-exposure night sky photography. Each of them has their own strengths and weaknesses, from the portability factor to maximum payload capacity. I’ll do my best to explain why the overall user experience is the number one factor to consider when choosing a portable tracking camera mount.

How to Use a Star Tracker

A star tracker’s job is to match the rotation of the Earth so that you can take long exposure images (at nearly any focal length) of the night sky. To properly track the stars that appear to move across the night sky each night, a star tracker must be polar aligned and balanced.

To polar align an equatorial mount for astrophotography (including a small camera tracker), you need to adjust the altitude and azimuth of the base so that the polar axis of the mount is aligned with the celestial pole. In the northern hemisphere, we have the advantage of using the north star, Polaris, to aid in this process.

A portable star tracker with a ball head and DSLR camera attached.

Without using a star tracker, the stars in the night sky will begin to trail after about 15-30 seconds, depending on the focal length of the lens used. This is because the Earth is spinning on its axis, while the night sky is fixed. Amateur photographers using a stationary tripod can use the 500 rule as a guide for choosing the ideal shutter speed, but a star tracker removes this limitation altogether.

When a tracking camera mount is used, a small motor slowly rotates your camera in right-ascension, effectively matching the apparent movement of the night sky, and freezing it in its tracks. The image below shows you what a 3-minute exposure using a 400mm lens would like without using a star tracker.

Long exposure images (180-seconds) shot at 400mm with and without tracking.

Luckily for amateur astrophotographers and photographers, there are a lot of great star tracker options to choose from these days. Unlike a heavy equatorial telescope mount, a star tracker is portable, small, and lightweight. Because of their small size and compact profile, they’re usually a lot more affordable, too.

The star tracker category includes small EQ mounts that can carry a camera and lens combo, whether it’s for wide-angle Milky Way photography or deep sky imaging with a telephoto lens. Wide-angle nightscapes and Milky Way panoramas are the star trackers strong point. These types of projects usually involve traveling to a remote location, where packing light is necessary.

If you’ve ever seen a detailed photo of the Milky Way like the one below, chances are the photographer used a star tracker to collect sharp, long exposure images with their camera and lens.

The Milky Way from a dark sky location. Stack of 60 x 2-minute exposures at ISO 1600.

A star tracker will usually include a polar scope, which is used to help find the north celestial pole and adjust the mount accordingly. A star tracker that has been properly polar aligned will match the exact apparent rotation of the night sky to freeze deep sky objects in place.

Don’t expect these little units to carry a heavy telescope, although small refractors are an option if you’ve got a counterweight system to help balance things out. As you’ll soon see with the Fornax Mounts LighTrack II, a counterweight system is often an additional option from the base star tracker package.

In fact, a lot of the star trackers available online today come in a potentially confusing number of packages and bundles. My advice is that you invest in a system that can not only handle your intended payload (and then some) but also provide you with features that make imaging in the field easier and more enjoyable.

Popular Models in the “Star Tracker” Category

If you are a beginner in the world of astrophotography (see my beginners guide), investing in a tracking camera mount is the single biggest advancement you can make in terms of gear. You can now let the exposure time do the heavy lifting without relying on fast optics and high ISO settings to collect a decent amount of signal.

The following tracking camera mounts share many similarities, including the ability to track the night sky at different speeds. Before investing in a dedicated star tracker for landscape or deep sky astrophotography, make sure the bundle you order includes everything you need to mount your camera and lens.

Which one should you invest your hard-earned money in for astrophotography? That will depend on the type of user-experience you are looking for, and my goal for this article is to highlight the key differences in the user experience for each mount.

If you’re just looking to shoot wide-angle astrophotography using a camera lens, I’ve got good news for you. All of the star trackers mentioned above are capable of accurately tracking the night sky for incredible long exposure images like the one below (including the most affordable option, the iOptron SkyTracker Pro).

Canon T3i and Rokinon 14mm F/2.8 lens on the iOptron SkyTracker Pro.

What They Do Best

These mounts are primarily designed for wide-angle astrophotography, meaning projects like Milky Way panoramas or mid-range focal length compositions using a telephoto lens in the 100-200mm range. That’s not to say that you can’t use a star tracker for high magnification deep sky imaging, but that will demand the most of your tracker, and a require a diligent setup routine.

The portable nature of a star tracker often leads to some of the most memorable deep sky astrophotography sessions in the field, as they offer you the freedom to travel to a dark sky location without a trunk full of gear. One of the most incredible astrophotography adventures of my life was setting up an iOptron SkyGuider Pro and William Optics RedCat 51 telescope to capture the Carina Nebula from Costa Rica.

The Carina Nebula from Costa Rica (9-minute exposure using a star tracker and small telescope).

It simply wasn’t possible to bring my computerized telescope mount to this location (on a plane), yet a star tracker fit in my carry-on bag and allowed me to collect tracked images of the night sky from the middle of the resort. These are the kinds of adventures you can expect when you invest in a portable star tracker for astrophotography.

Key Benefits of a Star Tracker

From my personal experience using star trackers for astrophotography from the backyard and beyond, I believe the absolute most important aspect to consider is the user experience. If the star tracker is not easy to use in the field, or the process of setting up takes too long, you won’t use it as much. That’s all there is to it.

As any experienced amateur astrophotographer will tell you, your motivation to stay up all night and image will vary. Any additional friction between you and a successful image has a way of affecting your decision process of stepping outside on a less-than-perfect night.

Don’t forget about the tear-down process either. If the clouds roll in and it looks like rain is coming, a lengthy teardown routine can turn into a stressful situation. Star trackers can usually be carried inside the house with all elements attached in a moments notice. The same can not be said for a full-blown deep sky astrophotography kit.

A star tracker should allow you to quickly get up-and-running under a clear night sky. It should be a pain-free experience that provides the freedom and flexibility to take amazing astrophotography images wherever, and whenever you want.

All of these photos were captured using a portable camera tracker mount.

Which Star Tracker is Right For You?

I am hesitant to state which star tracker is “best”, as I have found them all to have their strengths and weakness in terms of user experience in the field. I have not tested the Sky-Watcher Star Adventurer Pro mount, but the consensus from users online is that it is a great value for the money. You can see the results others are getting with this mount on Flickr.

I often see comments from beginners about being limited to a maximum exposure time using a particular mount before the stars begin to trail. My honest opinion is that these situations are almost always due to user error in the polar alignment and balancing procedure.

Each and every star tracker I have ever used for astrophotography was capable of sharp, 3-minute exposures using a focal length of up to 200mm. A portable star tracker must be accurately polar aligned and balanced to work properly. This may seem obvious to most people, but time and time again I see poor results being blamed on the hardware itself.

The iOptron SkyGuider Pro with a telescope attached.

My portable star tracking mounts have traveled with me to some amazing places and captured some of my favorite astrophotos. Both of the iOptron star trackers I am about to cover are extremely popular in the amateur astrophotography and nightscape photography community, and for good reason.

iOptron SkyTracker Pro

If you’ve watched any of my previous videos, you’ve probably seen the iOptron SkyTracker Pro in action. This ultra-lightweight star tracker is iOptron’s latest variation of their incredibly popular and affordable wide-angle astrophotography mount.

The SkyTracker Pro (not to be confused with the SkyGuider Pro) weighs just 2.6 pounds and houses everything you need for long exposure nightscapes in a little red (or black) box. A plastic box that is, with adorably simple controls to accelerate the RA axis to your intended target.

The iOptron SkyTracker Pro with a DSLR camera and wide-angle lens attached.

Weight: 1.5 lbs.

Max Payload: 6.6 lbs

Max Useful Focal Length: 200mm

Built-In Battery: Yes (Li-Poly 3.7V)

Built-In Polarscope: Yes

Autoguider Input: No

This camera mount was designed for wide-field nightscape images using a DSLR camera and lens. Many people have had great success using the SkyTracker with an ultra-wide-angle lens like the Rokinon 14mm F/2.8, all the way up to some heavier glass such as the Rokinon 135mm F/2.

It’s the most affordable star tracker I’ve used, and it has delivered exceptional results using a number of different camera lenses. One such instance was the time I used the SkyTracker Pro with my Canon EF 24-105mm F/4L Lens to shoot Mars and the Pleiades star cluster in the same frame.

iOptron SkyGuider Pro

The SkyGuider Pro is a big step up from the Tracker, offering a heavier payload capacity, a more robust design, and the ability to autoguide your images. The SkyGuider Pro is a top contender in this category with stellar reviews from experienced nightscape photographers.

This portable EQ mount fits in the palm of your hand, yet can handle up to 11 lbs of imaging gear. With the counterweight kit attached, the SkyGuider has no trouble with larger telephoto lenses and even small refractor telescopes such as the William Optics RedCat 51.

The North America Nebula in Cygnus. iOptron SkyGuider Pro with William Optics RedCat 51 attached.

Weight: 2.2 lbs.

Max Payload: 11 lbs

Max Useful Focal Length: 400mm

Built-In Battery: Yes (Li-Poly 3.7V)

Built-In Polarscope: Yes (Illuminated)

Autoguider Input: Yes

Beginners often get tracking and guiding mixed up or assume that they both mean the same thing. Tracking is the act of matching the rotation of the Earth using an RA (right ascension) motor, with the axis of the mount aligned with the celestial pole. Guiding is a specialized astrophotography technique that uses a secondary camera to lock-on to a guide star and sends small commands to the mount to improve tracking accuracy.

The iOptron SkyGuider Pro includes an ST-4 autoguide port that allows you to autoguide using the appropriate cabling and software on your computer. Although autoguiding is a powerful feature that allows for even longer exposures (and the benefits of dithering), it requires additional hardware to run.

The William Optics RedCat 51 is a great match for the SkyGuider Pro.

For smaller loads, such as a DSLR camera and 50mm lens, you can simply attach a ball head to the 1/4″ threaded socket on the mount. Heavier camera lenses or small telescopes will need to be mounted to the declination plate and utilize the counterweight system (shown above.)

For those that prefer to polar align their SkyGuider Pro electronically, the iOptron iPolar device was designed to fit neatly inside of this camera tracker. Be advised, that once you make this modification to the mount (or oder a version with the iPolar included), you lose an element of portability with the need for dedicated software control.

If you’re thinking about diving into the world of telescopes for astrophotography, I’d recommend the RedCat 51 Petzval APO to compliment the SkyGuider. This F/4.9 quadruplet apochromatic refractor is exceptionally sharp and delivers incredible wide-field images with a focal length of 250mm.

Sky-Watcher Star Adventurer

I have not had the pleasure of using a Sky-Watcher Star Adventurer mount myself, but I have seen a number of them in use first-hand at star parties and astronomy meet-ups. For a good look at the features and setup process of this mount, see Dylan O’Donnells video.

When comparing the specs between the iOptron SKyGuider Pro, and the Sky-Watcher Star Adventurer Pro, you’ll notice a number of similarities. For example, the “Pro Pack” includes a counterweight kit, wedge base, and a built-in illuminated polar scope.

Weight: 2.2 lbs.

Max Payload: 11 lbs

Max Useful Focal Length: 400mm

Built-In Battery: Yes (4 x AA)

Built-In Polarscope: Yes

Autoguider Input: Yes

The Star Adventurer includes a built-in WiFi, Android/iOS App control for those looking to control projects such as time lapses with your DSLR. Like the iOptron models I mentioned above, the Star Adventurer includes modes for solar, lunar, sidereal, and half sidereal tracking rates.

I really like that the Star Adventurer can run on 4 AA Batteries. Although it may seem like a step backward from a rechargeable li-poly battery, this feature may come in handy when your taking pictures nowhere near a source of power. Sky-Watcher reports that these batteries can power the mount for up to 72 hours, more than enough time for a night or imaging or two.

Without testing the Star Adventurer hands-on myself, I can’t say whether this mount delivers an experience that rivals the SkyGuider Pro. However, based on this video by Peter Zelinka, the process of setting up for a night of astrophotography looks to be strikingly similar.

Fornax Mounts LighTrack II

Fornax is a company based out of Hungary, and they are no stranger to astronomical equipment. Fornax has been manufacturing astronomical mounts for nearly 20 years, working on professional astronomical projects such as the HATNet Exoplanet Survey (Hungarian Automated Telescope) for discovering exoplanets.

The Fornax Mounts LighTrack II looks and acts differently than all of the other star trackers I previously mentioned. It uses a friction motor drive system that slowly sweeps an arm across the base of the mount. The fine friction strip helps the LighTrack II maintain balance, and was designed with strict production tolerances.

Like the other star trackers mentioned, the LighTrack II has 4 tracking speeds. Sidereal, Solar, Lunar, and Half. The “half” speed mode can be used to create nightscape images with terrestrial elements. For example, if you wanted to capture an interesting wide-angle landscape, but want to expose the night sky longer – you can, without the landscape being blurred.

Fornax Mounts LighTrack II.

Weight: 2.9 lbs.

Max Payload: 14 lbs

Max Useful Focal Length: 500mm

Built-In Battery: No

Built-In Polarscope: No (Additional Accessory)

Autoguider Input: Yes

The bundle I received from Fervent Astronomy included the MMW-200 wedge to mount the tracker to my tripod, and the counterweight kit (that I have not tested yet). The hardware is impressive, from the aluminum alloy components to the carbon-composite plastic housing for the electronics.

However, there are 2 colossal differences between the iOptron and Sky-Watcher camera trackers and the LighTrack II. The first is, this mount requires an external 12V power supply. There is no internal battery inside of the LighTrack II. So, if you plan on traveling with this mount you’ll need to bring a reliable battery or find an outlet and extension cord nearby.

The second is that the LighTrack II will only track your subject for 107 minutes, before having to return the tracking arm to its starting position. Luckily, you can use the panning control knob of your ball head to keep the camera stationary during this process.

The good news is, once you’ve powered the LighTrack II up, you’ll benefit from incredibly accurate unguided performance. Fornax lists that peak-to-peak unguided tracking error is less than 2 arcseconds in 8 minutes. I can confirm that the unguided performance of the Fornax LighTrack II is incredible and that the 3-minute images I’ve captured at 400mm were razor sharp.

Capturing the Lagoon Nebula and Trifid Nebula region with the Fornax LighTrack II was one of my first experiences using the mount, and it was a good one. The images were 3-minutes each at an effective focal length of 400mm with my camera system, and the unguided exposures were excellent.

Here is a look a single 180-second sub exposure using the LighTrack II with my Canon 60Da, William Optics RedCat 51, and the OPT Triad Ultra filter. I’d feel comfortable going to 5-minutes, wouldn’t you?

A single 3-minute, unguided exposure using the Fornax Mounts LighTrack II.

If you’re comparing the Fornax Mounts LighTrack II with the iOptron SkyGudier Pro, the accessories needed to complete a “full” package will send you well past the price of the SkyGuider Pro. The iOptron SkyGuider Pro full package includes the wedge, polar scope, and counterweight package. These items must be added on to the original price of the LighTrack II mount and purchased as a bundle.

It’s worth mentioning, that perhaps the LighTrack II should not be in the star tracker category at all. Due to its increased payload capacity, autoguiding capability, and accurate tracking, you may want to consider it to be a bridge between a camera tracker and a traditional equatorial telescope mount.

Star Tracker Comparison Chart

Here are the bare bones specs of the star trackers mentioned in this post. The listed “longest useful focal length” is merely a point a reference. In reality, I believe all of these trackers could handle a 2-minute exposure using an even longer lens.

Brand

Mount

Weight

Maximum Payload

Max. Useful Focal Length

Built-in Battery

Autoguide Port

iOptron

SkyTracker Pro

1.5 lbs.

6.6 lbs.

200mm

Yes

No

Sky-Watcher

Star Adventurer

2.2 lbs.

10 lbs.

300mm

Yes

Yes

iOptron

SkyGuider Pro

2.2 lbs.

11 lbs.

400mm

Yes

Yes

Fornax Mounts

LighTrack II

2.8 lbs.

13.2 lbs.

500mm

No

Yes

Final Thoughts

I believe that any mount that wants to compete in the “star tracker” category should have a built-in power option. I realize that many people are accustomed to traveling with an external power supply for various devices, but I am not one of them.

The iOptron SkyGuider Pro (and SkyTracker Pro) include an internal, rechargeable, li-poly 3.7V battery that can be charged with a mini-USB charging cable. This simple design feature means that I’ll reach for the SkyGuider when traveling light, or setting up for a brief imaging session. If you want to travel to a remote location with the LighTrack II, be prepared to power the mount using the cigarette lighter plug from your car.

In the end, the best camera tracker for astrophotography will always be the one you use the most. You can have the nicest equipment in the world, but if it doesn’t help you accomplish your final goal (pictures) on a consistent basis, it’s time to reflect on why you got into this crazy hobby in the first place.

Other Popular Star Trackers Available

There are new tracking camera mounts popping up every year. The models discussed in this post are not the only options available. Here is a short list of some of the other star trackers available today:

The clear sky chart for my area stated that the skies were to be clear for approximately 2 hours on Monday night. That was all the inspiration I needed to head out to the backyard and do some experimenting. Nights like this are perfect for trying out new techniques and equipment. Anything I get is a bonus.

I’ve tried imaging using my Canon EF 300mm F/4 L once before, but it was prime-time milky way season, and I just couldn’t do any more testing on that short July night. When time and opportunities are in limited supply, I always go with the tried-and-true system (Explore Scientific ED80 and Canon Xsi)

However, Monday night I gave my bird photography camera (Canon EOS 7D) a go at the night sky, with the 300mm lens in place of a telescope. But what target requires a nice wide field of view, short exposures, and is something I’ve never given any serious thought to? NGC 869 and NGC 884: Open star clusters in the constellation Perseus.

These pretty star clusters are now almost directly overhead around 8:00 pm.

Since I do not own an intervalometer for this DSLR, I was limited to 30″ exposures. Fortunately, star clusters tend to come out very nice using stacks of shorter exposure lengths. The photos above are a stack of 60 x 30″ frames at ISO 800. The second image is cropped to frame the double cluster in the center of the image.

I might have to try this setup for a full night of imaging on an area with interesting deep-sky treasures. A few of the obvious drawbacks of this system are the short exposure times, lack of light-pollution filter, and a non-modified DSLR. Not to mention, I am not automating the imaging session with BackyardEOS. For my laptop is in use, watching a Blu-ray in the garage;) (Wonders of the Universe)

Astrophotography with a Canon 7D

After capturing a respectable amount of photons on the double cluster in Perseus, I couldn’t resist trying this lens on the Orion Nebula. There it was, just taunting me in the distance. I snapped some 30-second exposures off with the 7D and the telephoto lens. It was fun to see the colorful images of the nebula appear on the LCD display, every 30 seconds. The photo below is the result of my quick trial.

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Sadr Star – Intersection of the Northern Cross

Photographing the Sadr Star in Cygnus

If you follow me on twitter, you may have noticed that I was poking around in the middle of the constellation Cygnus last weekend, specifically centered on to the extremely bright Sadr star. I really wanted to post a really snazzy wide field photo of this region on this blog, but I was unhappy with my results.

I set my mount and telescope up for imaging in the South, at the far edge of my backyard. This spot was a poor location for shooting straight up overhead at the constellation Cygnus for me, as I ran into trees by 1:30am. The result, only 1 hour of total exposure on a hot night. Even the stacked final image including 15 dark frames was noisy after stretching!

I was already sad about the trees, but after seeing my noisy photo, I was Sadr. (anyone?) Clearly, I need more time on it.

The night was not a complete waste. Aside from the mosquito bites and the ever constant worry from my neighbours “what is he doing out there!?”, I was able to snap this neat little photo of the Summer Triangle. The stars that make up this giant asterism are Altair, Vega and Deneb. For this shot, I used my Canon 70D and 17-40mm lens, riding on the Sky-Watcher mount. 15 – 40 second shots were stacked together for the final image.

The Summer Triangle

Tonight’s the Night – Gamma Cygni

With the almost first-quarter moon setting tonight around midnight, and clear, cool skies in the forecast for the Niagara region, it looks like I am set for round 2 tonight. Tomorrow night looks clear as well, will this be the weekend of the Sadr Star? That might be the nerdiest thing I have ever said. That’s not true.

Tonight, I will position the mount for an all-night-long session in Cygnus. My plan is to frame Gamma Cygni directly in the centre. From the other images of this area, it looks like I should pick up a lot of nebulosity throughout the frame.

My 30-day trial of Backyard EOS is still in effect, so I am happy to use it’s handy imaging features for another free night before shelling out the $50 US for the full version. A fair price for this impressive software. See the star map to the left for an idea of where I will be shooting tonight. If all goes well, my next post will be a portrait of the intersection of the Northern Cross.

Rosette Nebula – Stock Canon DSLR

How the Rosette Nebula looks with a Stock DSLR

Will an unmodified Canon DSLR pick up the red nebulosity?

Happy New Year! I was finally graced with some clear skies that showcased the beautiful winter milky way on Monday. The moon was about 19% lit, and didn’t set until about 10:30pm, so about half of data in the photo above was captured with the moon still out. The sky conditions were so fantastic on Monday, it was a shame I had to leave early to get a good night’s sleep for work the next morning.

The Rosette Nebula (Caldwell 49) is a large circular HII region. The open cluster NGC 2244 (Caldwell 50) is closely associated with the nebulosity, the stars of the cluster having been formed from the nebula’s matter.

Caldwell 49 – The Rosette Nebula
Imaged Monday, February 3, 2014

38 subs, 3.5 Minutes Each totaling 2 Hours 13 Minutes

I used the Explore Scientific 80ED telescope for this photo because the size of this object is quite large. I am quite happy with my end result, although I plan on processing the photo several more times to try and pull out as much detail as possible.

I highly recommend Noel Caboni’s “Astronomy Tools” action set for Photoshop. I found it very helpful when processing this image, and every other image I have taken. For the price of a cheap filter, you can drastically improve your astrophotos. Well worth it!

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Autumn Stars Arise

Autumn Stars – Pleiades Rising

Last Saturday I spent a very cold, but very dark and clear night at the RASC Observatory in Wellandport, Ontario. There were 4 of us that stayed the night, and I think every one of us complained about being under dressed! I began my night by shooting NGC 7293 – The Helix Nebula. I have never tried to shoot this object before, and to be honest, I didn’t think it was possible from Southern Ontario. I ended up with about 2 hours on it, but I think I will need to double that to really bring out the detail. As you can see, my unmodified Canon 450d makes this object look rather bluish-purple.

NGC 7293 – The Helix Nebula

My main focus for the night was the The Pleiades. This wonderful star cluster is located in the constellation Taurus the Bull. At this time of year, Taurus is just starting to rise high enough in the East to start photographing Messier Object 45, the Pleiades open-star cluster. I imaged this object last year, and was relatively happy with it, but I have learned a lot since then! The details of the above photo (of Pleiades) are as follows:

Removing Reflections in M45 image

Astrophotography processing The Pleiades

The autumn stars seem to shine extra bright as they bring in the winter constellations behind them. M45 can be surprisingly challenging to process, considering the inherent reflection issues that may arise. The healing brush in Adobe Photoshop is helpful in removing the unwanted halos and reflections in your image. You will definitely want to be careful not to remove any background stars or nebulosity in the process!

I will probably give it another shot once I have added more time. I am looking forward to re-doing Orion once it stays up for a little bit longer. Thanks for looking!